Variable prosthesis

ABSTRACT

The present teachings are directed to a shoulder prosthesis having an adjustable radial offset and/or angular inclination provided by relative rotation of an adapter interdisposed between a stem and a head. In one example, a prosthesis has a stem having a first longitudinal axis. The prosthesis can also include an adaptor including a first taper. The first taper can have a first taper axis. The prosthesis can include a head supported by the adaptor. The head can be selectively oriented and then coupled to the first taper and the combination can be selectively orientated and the coupled to the stem.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/309,973 filed Dec. 2, 2011. The entire disclosure of the aboveapplication is incorporated hereby by reference.

BACKGROUND

The present teachings relate to a prosthesis for replacing andreconstructing a portion of the joint and more specifically to a modularprosthesis.

The shoulder joint is considered to be one of the most complex joints inthe body. The scapula, the clavicle and the humerus all meet at theshoulder joint. The head of the humerus fits into a shallow socket ofthe scapula called the glenoid fossa to form a mobile joint. When thejoint is articulated, the humeral head moves in the glenoid fossa toprovide a wide range of motion. The shoulder joint may suffer fromvarious maladies including rheumatoid arthritis, osteoarthritis, rotatorcuff arthroplasty, a vascular necrosis, bone fracture or failure ofprevious joint implants. If severe joint damage occurs and no othermeans of treatment is found to be effective, then a total shoulderreconstruction may be necessary.

A shoulder joint prosthesis generally includes the replacement of theball of the humerus and, optionally, the socket of the shoulder bladewith specially designed artificial components. The bio-kinematics, andthus the range of motion in the shoulder vary greatly among prospectivepatients for reconstruction shoulder surgery. The humeral componenttypically has a metal shaft or stem with a body portion that is embeddedin the resected humerus and a generally hemispherical head portionsupported on the stem. The head slidingly engages a glenoid implant onthe glenoid fossa. During reconstructive surgery, the components of theprosthesis are matched with the bio-kinematics of the patient in aneffort to maintain the natural range of motion of a healthy shoulderjoint. Thus, a shoulder prosthesis design must be readily adaptable to awide range of bio-kinematics for prospectivepatients.

In this regard, shoulder prostheses are generally available as eitherunitary structures or modular components. With unitary shoulderprosthesis, a large inventory of differently sized prostheses must bemaintained to accommodate the different bone sizes and jointconfigurations of the prospective patients. With such unitary shoulderprosthesis, the patient is typically evaluated by x-ray to determine theapproximate prostheses size needed for reconstruction. A number ofdifferently sized prostheses are selected as possible candidates basedupon this preliminary evaluation. Final selection of the appropriatelysized prosthesis is made during the surgery. With unitary shoulderprosthesis, each design represents a compromise that is unable toachieve all of the natural range of motion of a healthy shoulder jointbecause of the fixed geometric configuration in their design.

Modular prostheses systems which reduce the need to maintain largeinventories of various sized components are well known in the art.Conventionally, the humeral prosthesis includes two components—a humeralstem component and a spherical head releasably coupled to the stem.Alternately, a three component design is known in which the stem andshoulder are interconnected with an adapter. In either of the two-pieceor three-piece designs, a radial offset or angulator inclination of thehead relative to the stem is provided in individual components. Forexample, in the three-piece design, an adapter may be configured with afixed radial offset of 2 millimeters or an angular inclination of 5degrees. Different radial offsets or angular inclinations are achievedthrough the use of different adapters or heads. In this regard,conventional modular shoulder prosthesis kits include multiple redundantcomponents such as adapters and heads to achieve a range of prostheticoptions. While providing an advantage over the unitary design inreducing the number of components needed, a rather large inventory ofhead components and/or adapter components must be maintained to providethe desired range of geometric configurations with the conventionalmodular shoulder prostheses. Therefore, there is a need for modularshoulder prostheses which are readily adaptable to provide a range ofgeometric configurations, i.e. radial offsets of angular inclinationwhile minimizing the number of components required.

SUMMARY

In accordance with the present teachings, a modular joint prosthesissystem is provided. Specifically, a humeral component for a totalshoulder prosthesis includes an adapter and a head component whichcooperate to provide a range of radial offsets and/or angularinclinations and which are adapted to be used in conjunction with astem.

In one embodiment, a humeral component for a total shoulder prosthesisis provided for adjustable radial offset of the head with respect to thestem. The shoulder prosthesis includes an adapter interposed between astem and a head. The adapter is eccentrically coupled to the stem suchthat relative angular positioning of the adapter on the stem will effecta first adjustment in the radial offset. Likewise, the head component iseccentrically coupled to the adapter as such that relative angularposition of the head on the adapter will effect a second radial offsetadjustment. By selectively positioning the adapter and the headcomponent with respect to the stem, an infinite adjustment of the radialoffset within a given range may be achieved. In one example, indicia areprovided at the interface between the adapter and the head to indicatethe offset vector (i.e., offset amount and direction).

In another embodiment, a humeral component for a total shoulderprosthesis is provided for adjustable angular inclination of the headcomponent relative to the stem component. The shoulder prosthesisincludes an adapter interposed between a stem and a head. The adapter iscoupled to the stem in a first angled or non-orthogonal orientation suchthat relative rotational positioning of the adapter on the stem willeffect a first adjustment in the direction of the angular inclination.Likewise, the adapter is coupled to the head in a second angled ornon-orthogonal orientation as such that relative rotational position ofthe head on the adapter will effect a second adjustment in the directionof the angular inclination. By selectively positioning the adapter andthe head component with respect to the stem, an infinite adjustment ofthe angular inclination within a given range may be achieved.

In et another embodiment, the present teachings include an adapterinterposed between a stem and a head. The adapter includes a ball studhaving a shank coupled to the stem and a ring coupled to the head. Thering has a spherical bearing surface which cooperates with a ballportion of the ball stud such that an angular adjusted between the ballstud and the ring may be effected. The ring is eccentrically coupled tothe head such that relative angular positioning of the ring in the headwill effect an adjustment in the radial offset.

The joint prosthesis system of the present teachings provides greatflexibility in the adjustment of important bio-kinematic parameters forthe prosthesis systems while minimizing the number of componentsrequired for the modular system.

Also provided according to the present teachings is a shoulderprosthesis comprising a stem having a first longitudinal axis. Theshoulder prosthesis can also include an adaptor including a first taper.The first taper can have a first taper axis. The shoulder prosthesis canalso include a plurality of indicia. The shoulder prosthesis can includea head rotatably supported by the adaptor. The head can have asemi-spherical articulating surface. The head can be coupled to thefirst taper and can be positionable relative to the stem throughrotation of the adaptor about the first taper axis for adjusting aradial offset of the head relative to the longitudinal axis of the stem.The plurality of indicia can indicate an alignment of the radial offset.

Further provided is a shoulder prosthesis comprising a stem having alongitudinal axis and a proximal face. The proximal face can define abore. The shoulder prosthesis can include an adaptor having a firstportion coupled to a second portion. At least a portion of the firstportion can be received within the bore of the stem to couple theadaptor to the stem. The first portion can also have a first diameter.The second portion can have a second diameter different than the firstdiameter, and can define a first taper. The adaptor can also include aplurality of indicia. The shoulder prosthesis can include a head havinga bottom face opposite a semispherical reticulating surface. The bottomface can have a second taper that mates with the first taper of thesecond portion to couple the head to the adaptor. The rotation of theadaptor relative to the stem can adjust the radial offset of the headrelative to the longitudinal axis of the stem. The plurality of indiciaon the adaptor can indicate an alignment of the radial offset.

According to the present teachings, provided is a shoulder prosthesiscomprising a stem having a longitudinal axis and a proximal face. Theproximal face can define a bore. The shoulder prosthesis can include anadaptor having a first portion opposite a second portion. At least aportion of the first portion can be received within the bore of the stemto couple the adaptor to the stem. The first portion can have a firstdiameter and can be positioned about a first axis. The second portioncan have a second diameter smaller than the first diameter. The secondportion can define a first taper and can be positioned about a secondaxis. The second axis can be offset from the first axis. The adaptor canalso include a plurality of indicia. The shoulder prosthesis can alsoinclude a head having a semispherical articulating surface and a bottomface opposite the semispherical articulating surface. The head can alsoinclude a third axis, which can be offset from the first axis and thesecond axis. The bottom face can have a second taper that mates with thefirst taper of the second portion to couple the head to the adaptor. Therotation of the adaptor relative to the stem can adjust the radialoffset of the head relative to the longitudinal axis of the stem. Theplurality of indicia on the adaptor can indicate an alignment of theradial offset.

A femoral prosthesis system according to various embodiments isdisclosed. The system can include a femoral head having an articulatingsurface defining a diameter and a generally opposed surface, a headfemale taper formed into the femoral head through the opposed surface,wherein a head center axis of the femoral head is offset a first radialdistance from a head taper center axis of the head female taper. Thesystem can further include an adapter having a first side and a secondgenerally opposed second side, the adapter further having an outersurface defining an adapter male taper and an adapter female taperformed into the adapter from the first side, wherein the adapter has anadapter center axis offset a radial distance from an adapter femaletaper axis. The system can also include a femoral stem having a body anda neck, wherein the neck extends at an angle relative to the body andthe neck has an outer surface that defines a neck male taper. Thefemoral head, the adapter, and the neck are selectively connected toachieve a selected femoral head offset relative to the femoral stem.

A femoral prosthesis system according to various embodiments isdisclosed. The system can include a femoral head sized and shaped forarticulation with at least one of an acetabulum or an acetabularprosthesis. The femoral head can have an articulating surface definingmore than a hemisphere and a diameter, an opposite surface generallyopposed to the articulating surface, a head female taper formed into thefemoral head through the opposite surface, and a head center axis of thefemoral head is offset a first radial distance from a head taper centeraxis of the head female taper, wherein the head center axis is definedthrough a portion of the articulating surface defining an axis of motionwith a pelvis of a patient. The system can further have an adapterhaving a first side and a second side generally opposed to the firstside, the adapter further having an outer surface defining an adaptermale taper and an adapter female taper formed into the adapter from thefirst side, wherein the adapter has an adapter center axis offset aradial distance from an adapter female taper axis. The system can alsoinclude a femoral stem having a body and a neck, wherein the neckextends at an angle relative to the body and the neck has an outersurface that defines a neck male taper. The femoral head, the adapter,and the neck can be selectively connected to achieve a selected femoralhead offset relative to the femoral stem.

A method of implanting a femoral prosthesis system according to variousembodiments is disclosed. The method can include determining ananteversion angle of a femur relative to a pelvis of the patient. Themethod can also include selecting an adapter having an adapter centeraxis and an adapter offset connection, wherein the adapter offsetconnection has an adapter connection center axis and selecting a femoralhead having a head center axis and an offset head connection that has ahead connection center axis. The selected adapter can be rotatedrelative to the selected femoral head to achieve a selected offset ofthe adapter connection center axis relative to the head connectioncenter axis. The selected offset of the adapter connection center axisrelative to the head connection center axis can be based on thedetermined anteversion angle.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present teachings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present teachings in any way.

FIG. 1 is an exploded front view of a modular shoulder prosthesis systemin accordance with the present teachings;

FIG. 2 is a normal view of the adapter and head components of the deviceillustrated in FIG. 1 shown in an assembled state;

FIG. 3 is an exploded front view of an alternate embodiment of themodular shoulder prosthesis system illustrated in FIG. 1;

FIG. 4 is a cross-sectional view of the adapter and head shown in FIG. 3arranged to provide a maximum radial offset;

FIG. 5 is a cross-sectional view of the adapter and head shown in FIG. 4and arranged to provide a minimum radial offset;

FIG. 6 is an exploded front view of a second alternative embodiment of amodular shoulder prosthesis system according to the present teachings;

FIG. 7 is a normal view of the adapter and head illustrated in FIG. 6shown in an assembled state;

FIG. 8 is an alternate embodiment of the modular shoulder prosthesissystem illustrated in FIG. 6;

FIG. 9 is a partial cross-sectional view showing the adapter and head ofFIG. 8 arranged to provide a maximum angular inclination;

FIG. 10 is an illustration of the adapter and head similar to that shownin FIG. 9 and arranged to provide a minimum angular inclination;

FIG. 11 is an exploded front view of a third alternative embodiment of amodular shoulder prosthesis system according to the present teachings;

FIG. 12 is a normal view of the adaptor and head components of thedevice shown in FIG. 11 oriented in a first position;

FIG. 13 is a normal view similar to FIG. 12 with the components orientedin a second position;

FIG. 14 is an exploded plan view of a variable femoral prosthesis,according to various embodiments;

FIG. 15 is a plan view along line FIG. 15-FIG. 15 of FIG. 14;

FIG. 16A is a cross-section view of a variable femoral head in a firstorientation;

FIG. 16B is a plan view of a variable femoral head in a secondorientation;

FIG. 16C is a plan view of a variable femoral head in a thirdorientation;

FIG. 17 is a cross-section view of a variable femoral head in a fourthorientation;

FIG. 18 is an exploded plan view of a variable femoral prosthesis,according to various embodiments;

FIG. 19 is an environmental view of an implanted variable hipprosthesis;

FIG. 20 is an environmental view of a variable femoral prosthesisillustrating variable varus and valgus positions; and

FIG. 21 is an environmental view of a variable femoral prosthesisillustrating variable anteversion and retroversion positions.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present teachings, application, or uses. It shouldbe understood that throughout the drawings, corresponding referencenumerals indicate like or corresponding parts and features. Although thefollowing description is related generally to a modular joint prosthesissystem which provides adjustment of the radial offset and/or angularinclination of the head relative to the stem, it will be understood thatthe system as described and claimed herein can be used in anyappropriate surgical procedure. Thus, it will be understood that thefollowing discussions are not intended to limit the scope of the presentteachings and claims herein.

With reference now to FIG. 1, shoulder prosthesis 20 in accordance withthe present teachings is illustrated to include a stem 22, an adapter 24and a head 26. Stem 22 includes a rod portion 28 adapted to be receivedin the medullary canal of the humerus. A plurality of fins 30 are formednear the upper end of rod 28 for locating and fixing the stem within ahumerus. A male taper 32 extends obtusely from rod 28 to provide alocation for interconnecting stem 22 with adapter 24. Male taper 32extends from stem 22 along axis 34. Stem 22 is of the type manufacturedand sold by Biomet, Inc. as a component in its Bi-Angular® ShoulderSystem.

Adapter 24 is a generally cylindrical disc having a female taper 36formed therein for receiving male taper 32 of stem 22. The outer surface38 of adapter 24 defines a male taper. Female taper 36 is eccentricallylocated in adapter 24 such that central axis 34 of female taper 36 isnot collinear with central axis 40 of adapter 24. Instead, central axis40 is radially offset from central axis 34 by an amount indicated as ra.

Head 26 includes a semispherical surface 42 defined about central axis44. Bottom face 46 is formed opposite semispherical surface 42 and has afemale taper 48 formed therein which is configured to receive adapter 24along central axis 40. In this regard, female taper 48 is formedeccentrically within head 26 such that a radial offset r_(b) existsbetween central axis 40 and central axis 44.

As previously described, the eccentric relationship of central axes 34,40 and 44 provide an arrangement whereby a relative rotationalpositioning of adapter 24 with respect to head 26 adjusts the radialoffset within a given range. As best seen in FIG. 2, relativepositioning of adapter 24 within female taper 48 of head 26 causescentroid 50 defined by female taper 36 to trace a helical path 52relative to centroid 54 defined by central axis 40. Helical path 62terminates at centroid 56 defined by central axis 34. A maximum radialoffset is achieved when centroid 50 is located directly oppositecentroid 56. Similarly, a minimum offset is achieved when centroid 50aligns with centroid 56. In one example, the maximum radial offset is 10mm and the minimum radial offset is 0 mm. However, one skilled in theart will recognize that the range of offset may be modified based on thedesign criteria for a given modular prosthesis system.

With continuing reference to FIG. 2, the shoulder prosthesis 20 isprovided with indicia 64 facilitating adjustment and alignment of theradial offset. Specifically indicia 60 includes a first set ofindicators 62 formed on adapter 24 and a second set of indicators 64formed on bottom face 46 of head 26. First and second indicators 62, 64have a magnitude value associated therewith indicating the amount ofradial offset. Furthermore, head indicators 64 include an enlargedarrowhead which indicate the direction of the radial offset. In thismanner, indicia 60 provide a radial offset vector which may be utilizedto precisely align adapter 24 and head 26 and achieve the desired radialoffset.

For example, as shown in FIG. 2, adapter indictor 62.10 associated witha 10 millimeter offset is aligned with head indictor 64.10 associatedwith 0,10 offset. Thus, the relative angular position of adapter 24 withrespect to head 26 shown in FIG. 2 provides a 10 millimeter offset andthe direction of the offset is indicated by arrowhead 64.10. The radialoffset may be reduced by removing adapter 24 from head 26, rotatingadapter 24 until indicia 60 are properly aligned and inserting adapter24 into female taper 48 of head 26. For example, an offset of 4millimeters would be obtained by aligning adapter indictor 62.4 withhead indictors 64.4 at which point a 4 millimeter offset in thedirection of arrowhead 64.4 would be achieved. In one example, athreaded through bore 66 may be formed in adapter 24 for receiving athreaded member to facilitate a disassembly of adapter 24 from head 26.In certain applications, a removeable plug (not shown) in the form of abio-compatible cement or the like may be disposed in bore 66 to minimizejoint fluid from entering the interface between the adapter 24 and thehead 26 through the bore 66.

With reference now to FIGS. 3 through 5, an alternate embodiment of thepresent teachings is illustrated in which the adapter has a first maletaper adapted to engage the stem and a second male taper adapted toengage the head. With reference now to FIG. 3, stem 22′ includes a rodportion 28′ and a female taper 32′ formed in the end opposite rod 28′which defines central axis 34′. Stem 22′ is of the type manufactured andsold by Biomet as a component of its Bio-Modular® Shoulder System.Adapter 24′ has a first male taper 36′ adapted to be inserted intofemale taper 32′ and a second male taper 38′ formed along central axis40′. Head 26′ includes a semispherical surface 42′ defined about centralaxis 44′. Bottom face 46′ has a female taper 48′ formed therein which isadapted to receive male taper 38′ of adapter 24′. Central axis 40′ isoffset from central axis 34′ as indicated at ra′ and central axis 44′ isoffset from central axis 40′ as indicated at r_(b)′. As in the firstembodiment, relative rotational positioning of adapter 24′ and head 26′provides an adjustable radial offset for shoulder prosthesis 20′.

With reference now to FIG. 4, central axis 34′ of male taper 36′ islocated directly opposite central axis 44′ of head 26′ to provide amaximum radial offset. With reference now to FIG. 5, head 26′ has beenrotated 180 degrees relative to adapter 24′ such that central axis 44′is collinear with central axis 34′. In this orientation, a minimumradial offset is provided. Indicia similar to that described above withreference to FIG. 2 facilitates alignment of shoulder prosthesis 20′.

Based on the foregoing detailed description, one skilled in the art willreadily recognize that one aspect of the present teachings is directedto an adapter and head having eccentric configurations such that arelative rotation therebetween provides an adjustable range of offsetconfiguration.

With reference now to FIGS. 6 through 10, a second alternativeembodiment of the present teachings is illustrated which provides foradjustment of the angular inclination between the stem component and thehead component in a manner similar to that described with reference tothe radial offset. Specially, the shoulder prosthesis system 120 of thesecond alternative embodiment includes a stem 122, a head 124 having afirst angular orientation and an adapter 126 interconnecting the stem122 and the head 124 such that the adapter 126 has a second angularinclination. The adapter 124 is configured to be rotatably positionablewith respect to the head 126 such that the angular inclination of thehead 126 relative to the stem 122 may be adjusted.

With specific reference to FIG. 6, shoulder prosthesis 120 includes stem122 having rod 128 extending therefrom. A plurality of fins 130 areformed longitudinally along rod 128 parallel to central longitudinalaxis A near the upper end of stem 122. A male taper 132 extends from rod128 at an obtuse angle a with respect to the central longitudinal axis Aand defines a central axis 134.

Adapter 124 is a generally cylindrical disc having a female taper 136formed therein. The outer surface of adapter 124 defines a male taper138. The central axis 140 of adapter 124 is configured at a firstangular orientation with respect to central axis 134. Specifically,central axis 140 is defined by the angle at which female taper 130 isoriented relative to the bottom surface 125 of adapter 124. In oneexample, central axis 140 is disposed at a +5 degree angular inclinationwith respect to central axis 134.

Head 126 includes a semispherical surface 142 and a flat bottom face 146having a female taper 148 formed therein. Female taper 148 definescentral axis 144 which is disposed at an angular inclination relative toa central axis 140. Specifically, central axis 144 is defined by theangle at which female taper 144 is oriented relative to bottom face 146.In one example, central axis 144 is disposed at a −5 degree angularinclination with respect to central axis 140.

The relative rotational position of adapter 124 with respect to the head126 defines the adjustment to the prosthesis inclination relative tocentral axis 34. For example, as illustrated in FIG. 6, adapter 126provides a +5 degree inclination which is canceled by the −5 inclinationprovided in head 126. Thus, when adapter 124 and head 126 are assembleda net zero angular inclination is achieved. An angular adjustment may beprovided by rotating adapter 124 relative to head 126 such that a netangular inclination is provided. For example, when adapter 124 isrotated clockwise 90 degrees, the angular inclination of central axis140 combines with the angular inclination of central axis 144 to providea +5 degree angular inclination of head 126 relative to central axis134. Likewise, an additional 90 degree rotation of adapter 124 willprovide an overall adjustment of +10 degrees in the angular inclination.In one example, a range of angular inclination is provided between OQand IOQ. However, one skilled in the art will recognize that the rangeof angular inclination may be modified based on the design criteria fora given modular prosthesis system.

With continuing reference to FIG. 7, adapter 124 and head 126 areprovided with inclination indicia 160 which facilitates identificationof the magnitude and direction of the angular inclination provided byshoulder prosthesis system 120. Specifically, angular indicia 160includes a first indictor 162 on adapter 124 and a plurality of secondindicators 164 provided on bottom face 146 of head 126. Adapterindicator 162 is an arrowhead which indicates the direction of theangular inclination. Head indicators 164 provide a magnitude of angularinclination as well as an alignment mark which cooperates with adapterindictor 162 to provide the angular inclination vector (i.e. magnitudeand direction).

With reference now to FIGS. 8 through 10, an alternate embodiment to thesecond alternative embodiment is illustrated in which the adapter has afirst male taper adapted to engage the stem and a second male taperadapted to engage the head. With reference now to FIG. 8, stem 122′includes a rod portion 128′ and a female taper 132′ formed in the endopposite rod 128′ which defines central axis 134′. Adapter 124′ has afirst male taper 136′ adapted to be inserted into female taper 132′ anda second male taper 138′ formed along central axis 140′. Head 126′includes a semispherical surface 142′ defined about central axis 144′.Bottom face 146′ has a female taper 148′ formed therein which is adaptedto receive male taper 138′ of adapter 124′. Central axis 140′ isangularly inclined relative to central axis 34′ and central axis 144′ isangularly inclined relative to central axis 140′. Relative rotationalpositioning of adapter 124′ and head 126′ provides an adjustable angularinclination for shoulder prosthesis 120′.

With reference now to FIG. 9, the angular inclination of central axis134′ of male taper 136′ is complementary with the central axis 144′ ofhead 26′ to provide a maximum angular inclination. With reference now toFIG. 10, head 126′ has been rotated 180 degrees relative to adapter 124′such that the angular inclination of central axis 144′ is opposingcentral axis 134′ to provide a minimum angular inclination.

From the foregoing description of various embodiments, one skilled inthe art will readily recognize that the present teachings are directedto a modular shoulder prosthesis in which the radial offset and/or theangular inclination (i.e. inversion and retroversion) of the headrelative to the stem may be adjusted by relative rotational positioningof an adapter interdisposed between the stem and head components of theshoulder prosthesis. In this way, a range of radial offsets and/orangular inclinations may be provided without requiring numerousadditional components. The various embodiments have discussed a radialoffset adjustment or an angular inclination adjustment independently;however, one skilled in the art will readily recognize that a shoulderprosthesis system may incorporate both aspects of a radial and angularadjustment. Where a single adapter utilized to interconnect the stem andthe head, an interrelationship exists between the radially offsetadjustment and the angular inclination adjustment. In combination, asystem could be employed which utilized two intermediate adapters suchthat the radial offset and angular inclination adjustment are isolatedand thus independent. For example, the interface between a first adapterand a second adapter would provide the desired radial adjustment asdescribed in particular reference to the first embodiment and theinterface between the second adapter and the head would provide theangular inclination as described with reference to the secondalternative embodiment. In such a system, each of the radial offset andangular inclination adjustments would be provided by a single interface,thereby minimizing the interrelation between both adjustments resultingfrom a single intermediate adapter.

With reference now to FIGS. 11-13, a third alternative embodiment of thepresent teachings is illustrated which provides for adjustment of boththe radial offset and the angular inclination. Specifically, theshoulder prosthesis 210 is provided and includes a stem 212, an adaptor214 and a head 216. The stem 212 includes a longitudinal axis A alongits length and further includes a rod portion 218 adapted to be receivedinto the medullary canal of the humerus. A plurality of fins 220 areformed near the proximal end of the rod 218 for locating and fixing thestem 212 within the humerus whereby the proximal end of the rod 218 hasa substantially larger body than that of the distal end and includes aproximal face 222 having a bore 224 formed therein along a central axis226 for receiving the adaptor 214. The proximal face 222 extends fromthe stem 212 along axis 226 and provides a location for interconnectingthe stem 212 with the adaptor 214. Further, the proximal face 222provides sufficient clearance for angular and radial adjustments of theadaptor 214 and the head 216 as will be discussed in more detail below.

The adaptor 214 is a generally cylindrical member including an outerring 228 having a central axis 230 and a ball stud 232 rotatablyconnected to the ring 228. The ring 228 includes an attachment aperture234 having a central axis 236

formed therethrough for rotatable engagement with the ball stud 232. Thering 228 further includes an outer surface having a male taper 238 forengagement with the head 216.

The ball stud 232 includes a shank segment 233 for engagement with thebore 224 of the stem 212 and a divided ball segment 240 for attachmentto attachment aperture 234 of the ring 228. The ball stud 232 furtherincludes a second bore 242 formed therein for interaction with afastener 244 for selectively securing the ring 228 to the ball stud 232in a fixed orientation. Fastener 244 includes a wedge portion 254 and aset screw 256 as best shown in FIG. 11. Set screw 256 is received by acentral bore of the wedge 254, whereby as the set screw 256 is driveninto the wedge 254, the wedge 254 expands within the attachment aperture234 of the ring 228 thereby securing the ring 228 and ball stud 232 in afixed relationship. In this regard, the central axis 236 of the ballstud 232 is concentric with central axis 226 of the proximal face 222and is received by the attachment aperture 234 such that the centralaxis 236 of the ball stud 232 is eccentric to the central axis 230 ofthe ring 228 as indicated by ra.

The head 216 is rotatably supported by the adaptor 214 and includes asemispherical surface 246 defined about a central axis 248 adapted formating engagement with the glenoid cavity of a scapula. The head 216further includes a bottom surface 250 formed opposite the semisphericalsurface 246 having a female taper 252 for mating engagement with themale taper 238 of the ring 228. In this regard, the female taper 252 isreceived eccentrically within the head 216 such that a radial offsetr_(b) exists between the central axis 230 of the ring 228 and thecentral axis 248 of the head 216. While the present teachings disclose ahead 216 for mating engagement with the glenoid cavity of a scapula, itis anticipated that the head 216 could also be received by a prostheticdevice replacing a severely damaged glenoid cavity and should beconsidered within the scope of the present teachings.

As previously described, the eccentric relationship of the central axes230, 236 and 248 provides an arrangement whereby a relative rotationalpositioning of the adaptor 214 with respect to the head 216 or arelative rotational positioning of the adaptor 214 with respect to theball stud 232 or a combination thereof adjusts the radial offset of thehead 216 relative to the longitudinal axis A of the stem 212.

With particular reference to FIG. 13, relative positioning of the head216 to the longitudinal axis A of the stem 212 is accomplished by afirst radial adjustment method. In the first radial adjustment method,the relative positioning of the ring 228 within the female taper 252 ofthe head 216 causes the central axis 248 of the head 216 to be rotatedrelative to the central axis 230 of the ring 228. The radial offsetbetween the central axis 248 and the central axis 230 is again denotedby rb at its minimum and by rb′ at its maximum value. FIG. 12 furthertraces the movement of axis 248 from rb to rb′ as indicated by path 249,while each position along path 249 signifies a potential adjustment ofthe head 216 relative to the longitudinal axis A of the stem 212.

With particular reference to FIGS. 12 and 13, relative positioning ofthe head 216 to the longitudinal axis A of the stem 212 is accomplishedby a second radial adjustment method. In the second radial adjustmentmethod, the relative positioning of the central axis 230 of the ring 228and the central axis 236 of the ball stud 232 causes the central axis248 of the head 216 to be rotated. Again, ra is used to designate theminimum offset between the central axis 230 of the ring 228 and thecentral axis 236 of the ball stud 232 while ra′ is used to designate themaximum offset. FIG. 13 further traces the movement of axis 248 from rato ra′ as indicated by path 251, while each position along path 251signifies a potential adjustment of the head 216 relative to thelongitudinal axis A of the stem 212. For discussion purposes, the head216 does not rotate relative to the ring 228 when making an adjustmentof the ball stud 232 relative to the ring 228, but it should beunderstood that both adjustment methods could be used concurrently toachieve an overall desired radial offset of the head 216 relative to thelongitudinal axis A of the stem 212.

In addition to providing a radial offset, the shoulder prosthesis 210further provides an angular adjustment of the head 216 relative to thelongitudinal axis A of the stem 212 for both inversion and retroversionadjustments. As best shown in FIG. 13, the central axis 248 of the head216 rotates about the central axis 236 of the ball stud 232, which isconcentric with the central axis 226 of the first bore 224. Aspreviously discussed, the divided ball segment 240 of the ball stud 232rotatably supports the ring 228 while the ring 228 supports the head216. By articulating either the head 216 or the ring 228, the ring 228will rotate on the divided ball segment 240 of the ball stud 232,thereby providing the head 216 with an angular adjustment relative tothe longitudinal axis A of the stem 212. For discussion purposes, thefirst and second radial adjustment methods are not utilized while makingan angular adjustment of the head 216, however, it should be understoodthat both adjustment methods may be used concurrently with the angularadjustment method and with one another to achieve an overall desiredangular and radial relationship of the head 216 relative to thelongitudinal axis A of the stem 212.

With continuing reference to FIGS. 12 and 13, the shoulder prosthesis isprovided with indicia 260 facilitating adjustment and alignment of theradial offset. Specifically, indicia 260 includes a first set ofindicators 262 formed on the ring 228 and a second set of indicators 264formed on the bottom face 250 of the head 216. First and secondindicators 262, 264 have a magnitude value associated therewithindicating the amount of radial offset. Furthermore, the head indicators264 include an enlarged arrowhead which indicates the direction of theradial offset. In this manner, indicia 260 provide a radial offsetvector which may be utilized to precisely align the adaptor 214 and thehead 216 and achieve the desired radial offset.

Disclosed above is a prosthesis that can be used in various embodimentsto repair a proximal portion of a humerus. The prosthesis, according tovarious embodiments, can also be used to repair or replace a proximalportion of a femur 522 (FIG. 19). A variable femur prosthesis 300 isillustrated in FIG. 14. The variable femoral prosthesis 300 can includeportions similar to the prosthesis illustrated in FIG. 1 as describedfurther herein. For example, the variable femoral prosthesis 300 caninclude a stem 302, an adapter 304, and a femoral head 306. Each of thestem 302, the adapter 304, and the femoral head 306 can be similar toprosthetic portions, such as those described above, but formed toreplace a proximal femoral portion. In addition, the various portions ofthe femoral prosthesis 300 can be similar to those commerciallyavailable, such as the Femoral Prosthesis sold as the Magnum™ FemoralProsthesis sold by Biomet, Inc.

The stem 302 can include a rod portion 310 that is formed to bepositioned within a femoral canal that can be reamed or formed within afemur, as illustrated in FIG. 19. The rod 310 can extend along an axis312 and can terminate at an upper edge 314 that can be positioned near aproximal portion of the femur. A neck 316 can extend from a proximalportion or terminal end of the rod 310. The neck 316 can include anexternal surface that defines a male taper 318. The neck 316 can extendalong an axis 320. The neck axis 320 and the rod axis 312 can form anangle 322 relative to one another. The angle 322 can generally be anobtuse angle.

The adapter 304 can be formed to include an external surface 330 thatdefines a male taper. The adapter 304 can also terminate in a surface332. A central axis 334 can be an axis that is defined through a centerof the male taper 330 or the end surface 332. A female taper 340 canalso be defined by a depression or bore of the adapter 304. The femaletaper 340 can define a central axis 342 that is eccentric or offset by aradial offset ra. The radial offset ra can be about 0.1 millimeters (mm)to about 10 mm, and further can be about 0.1 mm to about 5 mm, and canfurther be about 3 mm to about 5 mm, inclusive. Accordingly, the radialoffset ra of the adapter 304 can allow the adapter 304 to have an edgethat is positioned a greater distance from the neck 316 that anotheredge, as discussed further herein.

The adapter 304 can further include a further tapered surface or stemfacing taper surface 350 that can assist in providing clearance aroundthe neck 316 relative to the femoral stem 302. Additionally,depressions, such as a depression 352 can assist in inserting orengaging the adapter 304 into the head 306. It will be furtherunderstood, however, that the adapter 304 can include a threadedaperture similar to the threaded aperture 66 discussed above for removalof the adapter 304 from the head 306.

The femoral head 306 can be formed to have an exterior articulatingsurface 360 that is substantially smooth or otherwise provided toarticulate with a portion of either an acetabular prosthesis or anatural acetabulum of a patient. The exterior surface 360 of the femoralhead 306 can define any selected portion of a sphere. For example, theexterior surface 360 can define a hemisphere or more than a hemisphere.The femoral head 306 can also include a stem facing surface 362 intowhich the articulating surface 360 terminate. The stem facing surface360 can be substantially flat or in an appropriate configuration toallow for clearance of the anatomy relative to the femoral head 306.

Formed into the femoral head 306 through the stem facing surface 362 canbe a female taper 364. The female taper 364 can define a taper axis 366that is generally defined through a center of the female taper 364. Thefemoral head 306 can define a head middle axis 368 that is generallydefined through a center of the femoral head 306. The taper axis 366 andthe head axis 368 can be offset from one another radially by a radialoffset r_(b). The head radial offset r_(b) can be any appropriateoffset, such as within the range discussed above. For example, the headradial offset r_(b) can be about 0.1 mm to about 10 mm, further can beabout 0.1 mm to about 5 mm, and can further be about 3 mm to about 5 mm,inclusive. Accordingly, the femoral head 306 can include an externaledge or surface that extends beyond or is positioned away from a portionof the neck 316 in a first direction and a lesser distance away from theneck 316 in another direction.

As discussed above and further herein, the male taper 318, the femaletaper 340, the male taper 330, and the female taper 364, can be formedof any appropriate taper dimension. For example, a morse type taper orother self locking taper configurations can be provided. Self lockingtapers generally have complimentary angles of about 3-5 degrees.Accordingly, the male taper can have an external taper angle of about3-5 degrees from a central axis while the female taper can have aninternal complimentary taper of about 3-5 degrees central axis of thefemale taper. The taper dimensions can allow for a sufficiently lockingconfiguration or fixed configuration between the female and femaletapers when interconnected.

The femoral head 306 can be generally spherical and include a center 380where a radius extends from the center 380 to the surface 360 of thefemoral head 306. The radius 382 can be any appropriate size, such asabout 10 millimeters (mm) to about 50 mm, including about 10 mm to about35 mm, and further including about 11 to about 11 mm. The femoral head306 can define a portion of a sphere generally to the flat or rear side362. The portion of the sphere defined by the femoral head 306 can be anappropriate mount such as about 50% to about 95%, about 55% to about90%, and further including about 60% to about 80%. Accordingly, thefemoral head 306 can define more than a hemisphere of a sphere. Thearticulating surface 360 can be provided to articulate for a selectedrange of motion with the acetabular prosthesis or acetabulum of thepatient with a greater portion of the sphere defined by the femoral head306.

With reference to FIG. 15, a view from plane FIG. 15 in FIG. 14 isillustrated. Generally, the rear surface 362 of the femoral head 306 isillustrated. The femoral head 306 defines the female taper 364 discussedabove. Positioned within the female taper is the adapter 304. Asillustrated in FIG. 15, the adapter 304, when positioned within thefemale taper 364 defined by the femoral head 306, is offset by theradial offset r_(b) such that a first distance 390 is defined from oneedge of the adapter 304 to a first edge of the stem facing side 362 anda second distance 392 is defined between the adapter 304 and a secondedge of the stem facing side 362. The first distance 390 can differ fromthe second distance 392. The radial offset rb, therefore, positions theadapter 304 in a non-central or off center axis location within thefemoral head 306. Additionally, the female taper 340 of the adapter 304is offset a first distance 394 from a first edge of the adapter in asecond distance 396 from a second side of the adapter 304. The firstdistance 394 and the second distance 396 can differ. Accordingly, thefemale taper 340 includes the radial offset ra within the adapter 304.

It is further understood that the male and female tapers in therespective femoral head 306 and adapter 304 can be reversed. Similarly,the male taper 318 of the neck 316 and the female taper 340 of theadapter can be reversed. Thus, although respective axes of the male andfemale tapers can be maintained at radial offset positions, as discussedabove, the taper connections can be reversed in selected embodiments.

The female taper 340 can be offset from the center axis 366, asillustrated in FIG. 15. The adapter 304, however, can be rotated withinthe female taper 364 within the femoral head 306. Accordingly, thecenter 342 of the female taper 340 in the adapter 304 can move along anellipsis 400 by rotating the adapter 304 relative to the femoral head306.

The ellipsis 400 can be similar to the ellipsis 52 discussed aboverelative to the prosthesis 26. Accordingly, the center 342 of the femaletaper 340 of the adapter 304 can be moved relative to the center 366 ofthe femoral head 306. The amount of offset from the center 366 of thefemoral head 306 can be defined by the amount of rotation of the adapter304 relative to the femoral head 306. The amount of rotation can beindicated by a first marking 402 on the adapter 304 and one or moremarkings 404 positioned on the stem facing side 362 of the femoral head306. The adapter marking 402 can be similar to the markings 62 discussedin FIG. 2. The femoral head marking 404 can also be similar to theprosthesis markings 64 discussed in FIG. 2. Accordingly, the amount ofoffset that will be achieved by positioning the adapter 304 at aselected rotational position within the femoral head 306 can bedetermined by matching the indications 402 on the adapter 304 withmarkings 404 on the femoral head 306 and referring to the result.Appropriate markings can be provided to indicate an amount of change atabout 1 degree changes and/or about 2 degree markings. Generally, amaximum amount of ante version angle change markings can include aboutfive degrees to about 10 degrees. Similarly, the markings can show varusand valgus position and rotation or selection of position of the headcan be used to achieve a selected varus and valgus offset.

As discussed further herein, the radial offset rb of the femoral head306 and the radial offset ra of the adapter 304 can be used tocompensate for or achieve a selected amount of anteversion or angleoffset required due to acetabular prosthesis placement in or naturalacetabular anatomy of a patient. For example, an anteversion of apatient can be about five degrees to about 10 degrees. A prosthesis,however, positioned within a femur is positioned at a selectedorientation and must articulate with the acetabulum or an acetabularprosthesis in an appropriate manner. If a femoral prosthesis ispositioned within the femur at an orientation that does not allow for anachievement of a selected anteversion, the adapter 304 can be rotated toa selected position relative to the femoral head 306 to allow for thefemoral head 306 to be positioned at a selected orientation relative tothe remaining anatomy of the patient when connected to the neck 316. Thehead 306 and adapter 304 can, therefore, achieve a range of offsetangles between the femur and the pelvis. Accordingly, the adapter 304and the femoral head 306 can be provided to minimize inventory ofselected femoral heads, femoral stem prosthesis to be positioned of thefemur. Also, the range of offsets can allow for a selected orientationof the femoral prosthesis to be placed in the femur bone of the patientto maintain a selected bone mass relative to the femoral prosthesis.Moreover, an offset can be selected to compensate for less than optimalfemural stem 302 placement or acetabular prosthesis placement.

With continuing reference to FIG. 15 and addition reference to FIGS.16A, 16B, 16C, and 17, exemplarily placements of the adapter 304relative to the femoral head 306 are illustrated. With initial referenceto FIG. 16A, the femoral head 306 includes or defines the center headaxis 368, as discussed above. The female taper 340 and the adapter 304defines the middle axis of the taper 342. When rotated to a selectedposition and the adapter 304 is positioned in the femoral head 306, aselected offset of 410 can be achieved. The offset of 410 can be amaximum offset of the center of the female taper 342 relative to thecenter of the femoral head 368. The maximum offset 410 can be anyappropriate amount such as about one mm to about 20 mm, including abouttwo mm to about 15 mm, and further including about 2 mm to about 10 mm.The amount of offset can be selectively achieved, by rotating theadapter 304, as discussed in relation to FIG. 15.

As illustrated in FIGS. 16B and 16C the adapter 304 can also be rotatedto move the taper 340 in a direction transverse to a line or axis 307defined by the back face 362 of the femoral head 304. The line 307 canbe a center line of the head, or any other line that is generally in thesame plane or parallel to a plane of the back surface 362. Generally,the line 307 is provided to illustrate a “right” or “left” movement ofthe taper 340 relative to the head 306. “Right” and “left”, here, areunderstood to be relative terms, used to identify relative movement ofthe taper 340 and not necessarily an actual direction of the taper 340.

Regardless, as illustrated in FIG. 16B the taper 340 can be positioned adistance 307 a to the “right” of the line 307. The taper 340, however,is a distance 309 a from a line 309 defined relative to the head 306.The adapter 304 can also be rotated relative to the head 306 to placethe taper 340 a distance 307 b to the “left” of the line 307, asillustrated in FIG. 16C. When the taper 340 is to the “left,” however,the taper 340 can maintain the distance 309 a from the line 309. Thus,the taper 340 can be rotated “left” or “right” relative to the head 306(e.g. to create selected anteversion or retroversion offset, asillustrated in FIG. 21). In rotating the adapter 304, however, the taper340 can also be moved “up” and “down” (again it is understood that “up”and “down” are merely for descriptive differences in position and notnecessarily absolute positions of the taper 340) as illustrated in FIG.16A (e.g. to create selected varus and valgus offset as illustrated inFIG. 20).

By rotating the adapter 304, relative to the femoral head 306, an offsetof about, nearly, or exactly zero can also be achieved when the centerof the femoral head 368 and the center of the female taper 342 aresubstantially aligned, as illustrated in FIG. 17. It will be understoodthat having substantially zero offset can be understood to include asmall amount of error offset that is due to manufacturing tolerances,thus, a zero offset may actually be a non-zero amount. However,substantially no offset can be about 0.0 mm to about 0.3 mm, includingamount 0.0 mm to about 0.02 mm and further including about 0.01 to about0.015 mm.

As discussed above, by rotating the adapter 304 relative to the femoralhead 306, the selected offset can be achieved between the maximum “UP”offset 410, as illustrated in FIG. 16A and substantially zero offset412, illustrated in FIG. 17. Additionally, “left” and “right” offset canbe achieved by rotating the adapter 304. Accordingly, the singlecombination of the adapter 304 and the femoral head 306 can allow for afemoral prosthesis to be positioned within the patient at any of theplurality of offsets achievable by rotating the adapter 304 relative tothe femoral head 306. Additionally, in various embodiments, theinterconnection of the adapter 304 with the femoral head 306 can beachieved with substantially no further adhesives or connection mechanismbetween the various components, including the adapter 304, the femoralhead 306, and the femoral stem 302. It will be understood, however, thatin selected embodiments additional connection mechanisms can be providedbetween the various components. For example, adhesives or othermaterials can be positioned to interconnect the various components. Forexample, a mechanical interconnection, such as a screw or the like, canbe provided through various tapped or untapped holes formed within thefemoral head 306 or the adapter 304. Additionally, as discussed furtherherein, various portions of the prosthesis, according to variousembodiments, can be interconnected with fixation or locking portions toallow for achieving a selected orientation of the femoral head relativeto a femoral stem.

With reference to FIG. 18, a variable femoral prosthesis 450 isillustrated. The variable femoral prosthesis 450 can be similar to theprosthesis 410 illustrated above in FIG. 11. However, the femoralprosthesis can include a femoral stem 452 that extends along a firstaxis 454 and a neck portion 456 that extends along a second axis 458.Generally, an angle 459 can be defined between the stem axis 454 and theneck axis 458. The angle 459 can be an appropriate angle, such as anobtuse angle. The neck 456 can further define a bore 460 for receiving aball stud 462.

The femoral prosthesis 450 further includes an adapter 464. The adapter464 can define an exterior surface or male taper 466. Additionally, theadapter 464 defines an attachment aperture 468 for rotatable engagementwith the ball stud 462. The ball stud 462 includes a divided ballsegment 470 through which a fastener 472 can engage an internal bore474. The fastener 472 first passes through a wedge 476 and fixes thewedge 476 within the divided ball portion 470 once the divided ballportion 470 is in the attachment aperture 468. Accordingly, the wedge476 can wedge the divided ball portion 470 to engage the attachmentaperture 468 and the fastener 472 can hold the wedge relative to thedivided ball portion 470 within the adapter 464. Accordingly, theadapter 464 can be fixed relative to the neck 456. The divided ballportion 470 can also be made as one piece with the neck 456.

A femoral head 480 can include an articulation surface 482 similar tothe articulation surface of the femoral head 306 discussed above.Additionally, the femoral head 480 can include a stem facing surface 484into which a female taper 486 is defined. Thus, the articulation surface482 of the head 480 can define more than a hemisphere or selectedportion of a sphere, as discussed above. For example, the articulationsurface 482 can be about 55% to about 95% of a sphere, including about60% to about 80%, inclusive.

The femoral head 480 can define a central axis 490. Additionally, theadapter 464 defines an adapter central axis 492 and an aperture centralaxis 494 is defined through the adapter and the attachment aperture 468.The central axis 494 through the attachment aperture 468 is eccentric orreadily offset by a distance ra from the central axis 492 of the adapter464. Additionally, a center axis 496 through the taper 486 in thefemoral head 480 can be defined. Accordingly, a radial offset of n,between the center axes of the head 490 in the center axis of the taper486 can be formed. In this manner, the center axis 492 of the adapter464 can be positioned substantially in the center or aligned with thecenter axis 496 of the taper 486, but is offset by the radial distancerb from the center of the head axis 490. As discussed above, in relationto FIGS. 11-13, the adapter 464 can be rotated relative to the ball stud462 and the femoral head 480 can be rotated relative to the adapter 464to achieve selected radial offsets of the femoral head 480 relative tothe femoral neck 456. As discussed above, the adapter 464 can be rotatedrelative to the ball stud 232 that is fixed and within the neck 456 toachieve selected offsets due to the radial offset ra of the center ofthe ball stud 462 relative to the center axis 492 of the adapter 464.Similarly, rotating the femoral head 480 relative to the adapter 464achieves a selected offset due to the radial offset rb of the centeraxis 490 of the femoral head and center axis 496 of the taper 486.Again, appropriate offsets can be achieved within the range as discussedabove for achieving a selected implantation offset within a patient.

With reference to FIG. 19, a femoral prosthesis according to variousembodiments can be positioned relative to a pelvis 520 of a patient. Thefemoral prosthesis can be a part of a system that can include anacetabular prosthesis or a prepared acetabulum. An acetabulum can beprepared to receive a femoral head, such as the femoral head 306 or anacetabular prosthesis 522 can be positioned within the preparedacetabulum 520. It will be understood, however, that the femoral head306, according to various embodiments, can articulate with theprosthetic acetabulum or with a natural acetabulum. Additionally, thefemoral stem can be positioned in a femur 524 such as the femoral stem302. The adapter 304 can be positioned within the femoral head 306 in anappropriate manner to achieve an alignment along a selected axis, suchas an articulation axis 526 to achieve a selected position, such as ananteversion or other offset position, as discussed herein, of the femur524 relative to the pelvis 520 after implantation. As discussed above,the adapter 304 can be rotated relative to the femoral head 306 toachieve the selected offset.

In implanting and preparing to implant the variable prosthesis, such asthe variable femoral prosthesis 300, a surgeon can determine a desiredoffset, including at least one of an anteversion angle, a retroversionangle, a varus angle, or a valgus angle. In one example, the surgeon canreview image data or visually inspect and manually measure the patientto determine a selected or optimal offset. The head, adapter, and stemcan then be properly rotated to achieve the selected offset and thevariable prosthesis can be implanted. In various embodiments, thesurgeon may also re-measure, initially measure, or visually inspect thepatient after preparing or implanting at least one of the stem 302 orthe acetabular prosthesis 522 to determine an optimal angle or offset.Again, the head, adapter, and stem can then be properly rotated toachieve the selected offset and the variable prosthesis can be implantedbased on the measurement and/or determination after preparing orimplanting at least one of the stem 302 or the acetabular prosthesis522. Thus, the determination of the appropriate offset can be made andthe appropriate position of the head and adapter can be made at aselected appropriate time.

As an example, an illustrated in FIGS. 20 and 21 the variable femoralprosthesis can be positioned within a patient in the selected offset,which can include a selected anteversion angle, retroversion angle,varus angle, or valgus angle. The offset of the variable prosthesis,however, can be positioned within the patient based upon an orientationof an adapter 304 relative to the femoral head 306 and the femoral stem302. As discussed above and illustrated in FIGS. 16A and 17, the adapter304 can be rotated relative to the femoral head 306 to position thetaper 340 generally along an axis, but closer to or further away from acentral axis that is defined through an apex of the head 306. It willalso be understood, however, as illustrated in FIGS. 16B and 16C, thatthe taper 340 can be rotated relative to a central axis definedgenerally on a plane defined by the backside of the head 306 to move thetaper 340 between two sides of the femoral head 306.

As illustrated, therefore, positions of the taper 304 and the femoralhead 306 relative to the femoral stem 302 allows for movement of thefemoral head 306 relative to the femoral stem 302. The adapter 304 canbe rotated around within the femoral head 306 in substantially 360degrees. Accordingly, movement of the femoral adapter 304 relative tothe femoral head 306 and the stem 302 can form or move the head 306 in avarus direction 550 or a valgus direction 552, as illustrated in FIG.20. The direction can be based on the patient's anatomy and relative tothe femoral stem 302 that defines an axis 302 a generally through thestem 302.

In a selected orientation, the femoral head can be aligned with an axisthrough a trunion 554 or neck of the femoral stem 302, such that thefemoral head 306 can include the central axis that is substantiallyaligned with the axis of the trunion 554. In a selected orientation,however, the rotation of the adapter 304 and/or the femoral head 306 canmove the femoral head 306 to a varus direction 550, as illustrated byphantom head position 550 a. Alternatively, the adapter 304 and/or thefemoral head 306 can be rotated to move the femoral head 306 in a valgusdirection 552, as illustrated in phantom head position 552 a. The varusand valgus directions, 550, 552, respectively, can be achieved withinthe anatomy of the patient.

In addition, due to rotation of the femoral head 306 and/or the femoraladapter 304, the femoral head 306 can also be moved in an anteversiondirection 560 or in a retroversion direction 562, as illustrated in FIG.21. Again, the femoral stem 302 can define the central axis 302 a andthe trunion or neck axis 554 that can be aligned with a central axis ofthe femoral head 306 in a selected position. The femoral adapter 304and/or the femoral head 306, however, can be rotated to move the femoralhead 306 in an anteversion direction 560 as shown in phantom headposition 560 a. Alternately, the adapter 304 and/or the femoral head 306can be rotated to move the femoral head 306 in a retroversion direction562 as shown by phantom head position 562 a. Again, the anteversion andretroversion directions, 560, 562, respectively, can be anatomicalpositions relative to the femur 524 and the pelvis 520.

Accordingly, movement of the femoral head 306 in any one of the varusdirections, valgus direction, anteversion direction, or retroversiondirection can be substantially relative to the patient. The rotation ofthe femoral head 306 and/or the adapter 304 relative to the stem 302positioned in the femur 524, however, can achieve the various directionsrelative to the pelvis 520 to achieve a selected position of the femur524 relative to the pelvis 520. Thus, the combination of the head 306and the adapter 304 can achieve various and selection offsets of thehead 306 relative to the stem 302.

It is understood that the implantation of the femoral prosthesis,according to various embodiments, can be achieved with generally knownsurgical techniques. Generally, access can be achieved to the femoraljoint and either or both of the femur 524 and the pelvis 520 can beprepared for implantation for selected prostheses. The variableprosthesis as discussed herein, however, can allow for a physician orsurgeon to implant a prosthesis with an appropriate offset, as discussedabove, even after preparing the acetabulum and the femur to maintain aselected amount of bone after implantation or based upon an anatomy orbone structure of a patient. For example, achieving a position of afixed or non-variable prosthesis relative to a patient may be difficultif a bone structure or anatomy does not allow for extensive reaming orpreparation for various prostheses. Nevertheless, the prosthetic devicescan be specifically designed for selected patients, but a variableprosthesis can minimize selection and minimize inventory at a selectedimplantation facility therefore allowing greater variability with asingle prosthetic device for multiple patients.

In reference to all of the above-described embodiments, various taperedsurfaces have been referenced at interfaces between the stem, adapterand head. In one example, these tapered surfaces are configured as selflocking tapers, such as morse-type tapers which provide a self lockinginterface. Locking tapers can include complementary angles of about 3degrees to about 5 degrees, inclusive. While morse-type tapers aredescribed herein, one skilled in the art will readily recognize thatother means may be incorporated for providing a locking interfacebetween the various components of the prosthesis system. In this regard,one or more interfaces may be interlocked with the use of an additionalfastener to insure locking engagement therebetween.

Moreover, the various components can be formed with generally knowntechniques. For example, the heads, adapters and stems can be formedwith various forging or casting techniques and selected finishingprocedures can be applied to their respective surfaces. The tapers canalso be formed in the various components with selected millingtechniques or can be formed with casting and forging techniques.

While specific examples have been described in the specification andillustrated in the drawings, it will be understood by those of ordinaryskill in the art that various changes can be made and equivalents can besubstituted for elements thereof without departing from the scope of thepresent teachings. Furthermore, the mixing and matching of features,elements and/or functions between various examples is expresslycontemplated herein so that one of ordinary skill in the art wouldappreciate from the present teachings that features, elements and/orfunctions of one example can be incorporated into another example asappropriate, unless described otherwise, above. Moreover, manymodifications can be made to adapt a particular situation or material tothe present teachings without departing from the essential scopethereof. Therefore, it is intended that the present teachings not belimited to the particular examples illustrated by the drawings anddescribed in the specification, but that the scope of the presentteachings will include any embodiments falling within the foregoingdescription.

1. (canceled)
 2. A method of implanting a prosthesis system in apatient, comprising: determining an anteversion angle of a natural bonerelative to a pelvis of the patient; selecting an adapter having anadapter center axis and an adapter offset connection, wherein theadapter offset connection has an adapter connection center axis;selecting a head having a head center axis and an offset headconnection, wherein the offset head connection has a head connectioncenter axis; selecting a distance offset between the adapter connectioncenter axis and the head connection center axis based on the determinedanteversion angle; and rotating the selected adapter relative to theselected head to achieve the selected distance offset between theadapter connection center axis and the head connection center axis. 3.The method of claim 2, wherein selecting the distance offset includesselecting a radial distance offset between the adapter connection centeraxis and the head connection center axis.
 4. The method of claim 2,wherein the prosthesis comprises a femoral prosthesis, the natural bonecomprises a natural femur, and the selected head comprises a selectedfemoral head.
 5. The method of claim 2, wherein the adapter offsetconnection includes a female locking taper.
 6. The method of claim 4,further comprising: providing the adapter connection center axissubstantially through a center of the adapter offset connection.
 7. Themethod of claim 2, wherein rotating the selected adapter relative to theselected head to achieve the selected distance offset between theadapter connection center axis and the head connection center axisincludes forming the selected distance offset at or between a maximumoffset and a substantially zero offset.
 8. The method of claim 7,wherein selecting the head includes selecting a head member having acurved articulating surface configured to articulate relative to thepelvis when replacing at least a portion of the natural bone.
 9. Themethod of claim 8, wherein selecting the head further includes selectingthe head member to include a substantially planar surface opposed to thecurved articulating surface and configured to interconnect with a stem,wherein the stem is configured to be implanted into the natural bone.10. The method of claim 7, wherein the maximum offset is defined aspositioning the adapter connection center axis away from the head centeraxis a maximum distance.
 11. The method of claim 7, wherein thesubstantially zero offset is defined as generally aligning the adapterconnection center axis and the head center axis.
 12. A method ofimplanting a femoral prosthesis system in a patient, comprising:selecting a femoral head having a head center axis, an offset headconnection, and a curved articulating surface, wherein the offset headconnection has a head connection center axis that is displaced adistance from the head center axis, wherein the curved articulatingsurface is configured to articulate within at least one of a anacetabular prosthesis or an acetabulum in a pelvis of the patient,selecting an adapter having an adapter center axis and an adapter offsetconnection, wherein the adapter offset connection has an adapterconnection center axis that is displaced a distance from the adaptercenter axis; selecting a distance offset between the adapter connectioncenter axis and the head connection center axis based on a determinedanteversion angle of a femur relative to the pelvis of the patient; androtating the selected adapter relative to the selected femoral head toachieve the selected distance offset between the adapter connectioncenter axis and the head connection center axis.
 13. The method of claim12, wherein the selected distance offset is a radial distance offsetbetween the adapter connection center axis and the head connectioncenter axis.
 14. The method of claim 12, further comprising measuring aposition of the femur relative to the acetabulum in the pelvis todetermine the anteversion angle.
 15. The method of claim 14, furthercomprising: obtaining access to a hip joint between the femur and thepelvis; resecting a natural femoral head of the femur; and implantingthe selected femoral head to replace the resected femoral head.
 16. Themethod of claim 15, wherein the selected distance offset is at orbetween a maximum offset and a minimum offset; wherein the maximumoffset is a maximum displacement of the adapter connection center axisand the head center axis; and wherein the minimum offset is asubstantial alignment of the adapter connection center axis and the headcenter axis.
 17. The method of claim 16, further comprising: implantinga femoral stem into the femur; connecting the selected adapter to thefemoral stem; and connecting the selected femoral head to the selectedadapter.
 18. The method of claim 17, wherein connecting the selectedfemoral head to the selected adapter includes: fixing the selectedfemoral head to the selected adapter, wherein fixing the selectedfemoral head to the selected adapter occurs after rotating the selectedfemoral head to the selected adapter to achieve the selected distanceoffset.
 19. A method of implanting a prosthesis system in a patient,comprising: selecting an adapter having an adapter center axis and anadapter offset connection, wherein the adapter offset connection has anadapter connection center axis; selecting a femoral head having a headcenter axis and an offset head connection, wherein the offset headconnection has a head connection center axis; selecting a distanceoffset between the adapter connection center axis and the headconnection center axis based on an anteversion angle of a natural femurrelative to a pelvis of the patient; and rotating the selected adapterrelative to the selected femoral head to achieve the selected distanceoffset between the adapter connection center axis and the headconnection center axis.
 20. The method of claim 19, wherein selectingthe distance offset includes selecting a radial distance offset betweenthe adapter connection center axis and the head connection center axis.21. The method of claim 19, further comprising: providing the adapterconnection center axis substantially through a center of the adapteroffset connection.